The present invention relates to apparatus for fracturing cap and shaft of connecting rods manufactured by powder forging.
Known methods for fracturing cap and shaft of connecting rods are based in principle on the method of causing an "expanding force" to act on the inner surface of the large eye of the connecting rod by means of special devices, and increasing it until the breaking point of the connecting rod material is reached and cap and shaft are separated by fracture (See FIG. 6 of U.S. Pat. No. 4,569,109).
In order to be able to cause the fracture at a precisely preset point, notches are provided on the inner surface of the large eye and partly also on the outer surface thereof (See U.S. Pat. Nos. 4,569,109 and 4,693,139).
Fracturing methods are also known in which in the desired plane of fracture in the connecting rod holes are provided through which the forces required for fracture are introduced into the connecting rod material by "expander mandrels" (See FIG. 3 of U.S. Pat. No. 3,994,054).
Mechanical fracturing methods of this kind are particularly unsuitable for mass production, inter alia because of unfavourable frictional conditions, although methods have already been developed in which the expanding force is generated hydraulically (See U.S. Pat. No. 4,754,906). Methods of this kind are, however, technically very elaborate because of the high-pressure hydraulics required, and they do not yield optimum fracture results.
It is the object of the present invention to provide a completely novel apparatus for the fracture of connecting rods, which comprises a simple construction and yields improved fracture results.